HETEROMYS. ZAPUS. 257 



cially of the pes; nevertheless the pes with five perfect and separate 

 metatarsals and five functionally developed digits, claws not pecu- 

 liar. Tail greatly exceeding the trunk in length, very slender, scant 

 haired." (Coues. ) 



Sub. Fam. I. Zapodinae. 



<»(>. Xapus. 



I. "=!■ p. ini; M. ^-=3 = i8. 



I— i' o-o' 3-3 



Zapus. Coues, Bull. U. S. Geol. Surv. Terr., i, 2d ser., No. 5, p. 



253, 1875. Type, /). hudsonius. Zinim. 

 Napcozapus. Preble, N. Am. Faun., No. 15, i8yg, p. 33. Type, 



Z. insignis. Miller. 

 Eozapus. Preble, N. Am. Faun., No. 15, 1899, p. 37. Type, 



Z. setchuanits, Pousargues. 

 Internal cheek pouches; first digit of hand rudimentary, nail 

 flat, blunt: palms and soles naked, granulate, tuberculate, save heel 

 which is smooth; meatus large, antitragus much developed. Pelage 

 coarse. Skull delicate, papery construction; anteorbital foramen 

 very large and obliquely oval; malar extended until sutured with the 

 lachrymal; zygomatic arch slender, depressed; bullaj short, placed 

 transversely: rostrum attenuate anteriorly; interorbital constriction 

 moderate; no post-orbital process; interparietal large, nearly stjuare; 

 mastoids moderate; pterygoid fossa wide; pterygoid long, straight, 

 ending close to bulhe; palate with posterior rounded arch ending op- 

 posite last molars, and broadest anteriorly. Descending process of 

 mandible twisted diagonally outward and upward; coronoid falcate, 

 acute, higher than condyle. Upper incisors, sulcata, short, stout; 

 upper premolar absent in one sub-genus. 



A. Zapus, 



"Premolar present; enamel folds closelj- crowded; tail not 

 tipped with white; ears rather long; lower parts white or ochraceous." 



394. hudsonius. {Dipus), Zimm., Geog. Gesch. Mens. u. vierfuss, 

 Thiere., 1780, 11, p. 358. 

 labradoiius, Kerr., Anim. King., 1792, p. 276. 

 canadensis, Davies, Trans. Linn. Soc. Lond., 1798, Iv, p. 167. 

 americanus, Wagl., Nat. Syst. Amph., 1830, p. 23. 

 viicroctphalus, Harlan, Proc. Zool. Soc. Lond., 1839, p. i. 

 acadictis, Dawson, Edinb. New Phil. Journ., N. S., 1856, in, p. 2. 

 hardyi, Batchelder, Proc. N. Eng. Zool. Club, 1899, i, p. 5. 

 Type locality. Hudson Bay. 



